Process for the manufacture of a 2,3-dihydroxyquinoxaline, and 2,3-dihydroxyquinoxalines thus obtained

Abstract

A quinoxaline is oxidized by means of hydrogen peroxide in an inert solvent medium in the presence of water and of a catalyst selected from selenium and selenium compounds. The process applies to the preparation of substituted and unsubstituted 2,3-dihydroxyquinoxalines.

We claim: 
     
       1. A process for the manufacture of a 2,3-dihydroxyquinoxaline by oxidation of an unsubstituted quinoxaline or a quinoxaline substituted on the benzene nucleus at positions 5, 6, 7, and 8 by means of hydrogen peroxide in an inert solvent, wherein the oxidation is performed in the presence of water and a catalyst consisting of selenium oxide. 
     
     
       2. Process according to claim 1, characterized in that the catalyst is employed in a quantity of between 25 and 80 millimoles per mole of quinoxaline. 
     
     
       3. The process according to any one of the preceding claims, wherein the inert solvent is chosen from aliphatic alcohols, cyclohexanol, benzyl alcohol and dioxan. 
     
     
       4. The process according to claim 3, wherein the aliphatic alcohol is chosen from ethanol, n-propanol, n-butanol and polyethylene glycol. 
     
     
       5. The process according to claim 1, wherein at least part of the water employed is the water produced by the oxidation reaction. 
     
     
       6. The process according to claim 1, wherein a quantity of water not exceeding 35% of the weight of the inert solvent is added to the reaction mixture.